/*
MIT License

Copyright (c) 2019 SergeyBel

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
#include "AES.h"

AES::AES(const AESKeyLength keyLength) {
  switch (keyLength) {
    case AESKeyLength::AES_128:
      this->Nk = 4;
      this->Nr = 10;
      break;
    case AESKeyLength::AES_192:
      this->Nk = 6;
      this->Nr = 12;
      break;
    case AESKeyLength::AES_256:
      this->Nk = 8;
      this->Nr = 14;
      break;
  }
}

unsigned char *AES::EncryptECB(const unsigned char in[], unsigned int inLen,
                               const unsigned char key[]) {
  CheckLength(inLen);
  unsigned char *out = new unsigned char[inLen];
  unsigned char *roundKeys = new unsigned char[4 * Nb * (Nr + 1)];
  KeyExpansion(key, roundKeys);
  for (unsigned int i = 0; i < inLen; i += blockBytesLen) {
    EncryptBlock(in + i, out + i, roundKeys);
  }

  delete[] roundKeys;

  return out;
}

unsigned char *AES::DecryptECB(const unsigned char in[], unsigned int inLen,
                               const unsigned char key[]) {
  CheckLength(inLen);
  unsigned char *out = new unsigned char[inLen];
  unsigned char *roundKeys = new unsigned char[4 * Nb * (Nr + 1)];
  KeyExpansion(key, roundKeys);
  for (unsigned int i = 0; i < inLen; i += blockBytesLen) {
    DecryptBlock(in + i, out + i, roundKeys);
  }

  delete[] roundKeys;

  return out;
}

unsigned char *AES::EncryptCBC(const unsigned char in[], unsigned int inLen,
                               const unsigned char key[],
                               const unsigned char *iv) {
  CheckLength(inLen);
  unsigned char *out = new unsigned char[inLen];
  unsigned char block[blockBytesLen];
  unsigned char *roundKeys = new unsigned char[4 * Nb * (Nr + 1)];
  KeyExpansion(key, roundKeys);
  memcpy(block, iv, blockBytesLen);
  for (unsigned int i = 0; i < inLen; i += blockBytesLen) {
    XorBlocks(block, in + i, block, blockBytesLen);
    EncryptBlock(block, out + i, roundKeys);
    memcpy(block, out + i, blockBytesLen);
  }

  delete[] roundKeys;

  return out;
}

unsigned char *AES::DecryptCBC(const unsigned char in[], unsigned int inLen,
                               const unsigned char key[],
                               const unsigned char *iv) {
  CheckLength(inLen);
  unsigned char *out = new unsigned char[inLen];
  unsigned char block[blockBytesLen];
  unsigned char *roundKeys = new unsigned char[4 * Nb * (Nr + 1)];
  KeyExpansion(key, roundKeys);
  memcpy(block, iv, blockBytesLen);
  for (unsigned int i = 0; i < inLen; i += blockBytesLen) {
    DecryptBlock(in + i, out + i, roundKeys);
    XorBlocks(block, out + i, out + i, blockBytesLen);
    memcpy(block, in + i, blockBytesLen);
  }

  delete[] roundKeys;

  return out;
}

unsigned char *AES::EncryptCFB(const unsigned char in[], unsigned int inLen,
                               const unsigned char key[],
                               const unsigned char *iv) {
  CheckLength(inLen);
  unsigned char *out = new unsigned char[inLen];
  unsigned char block[blockBytesLen];
  unsigned char encryptedBlock[blockBytesLen];
  unsigned char *roundKeys = new unsigned char[4 * Nb * (Nr + 1)];
  KeyExpansion(key, roundKeys);
  memcpy(block, iv, blockBytesLen);
  for (unsigned int i = 0; i < inLen; i += blockBytesLen) {
    EncryptBlock(block, encryptedBlock, roundKeys);
    XorBlocks(in + i, encryptedBlock, out + i, blockBytesLen);
    memcpy(block, out + i, blockBytesLen);
  }

  delete[] roundKeys;

  return out;
}

unsigned char *AES::DecryptCFB(const unsigned char in[], unsigned int inLen,
                               const unsigned char key[],
                               const unsigned char *iv) {
  CheckLength(inLen);
  unsigned char *out = new unsigned char[inLen];
  unsigned char block[blockBytesLen];
  unsigned char encryptedBlock[blockBytesLen];
  unsigned char *roundKeys = new unsigned char[4 * Nb * (Nr + 1)];
  KeyExpansion(key, roundKeys);
  memcpy(block, iv, blockBytesLen);
  for (unsigned int i = 0; i < inLen; i += blockBytesLen) {
    EncryptBlock(block, encryptedBlock, roundKeys);
    XorBlocks(in + i, encryptedBlock, out + i, blockBytesLen);
    memcpy(block, in + i, blockBytesLen);
  }

  delete[] roundKeys;

  return out;
}

void AES::CheckLength(unsigned int len) {
  if (len % blockBytesLen != 0) {
    throw std::length_error("Plaintext length must be divisible by " +
                            std::to_string(blockBytesLen));
  }
}

void AES::EncryptBlock(const unsigned char in[], unsigned char out[],
                       unsigned char *roundKeys) {
  unsigned char state[4][Nb];
  unsigned int i, j, round;

  for (i = 0; i < 4; i++) {
    for (j = 0; j < Nb; j++) {
      state[i][j] = in[i + 4 * j];
    }
  }

  AddRoundKey(state, roundKeys);

  for (round = 1; round <= Nr - 1; round++) {
    SubBytes(state);
    ShiftRows(state);
    MixColumns(state);
    AddRoundKey(state, roundKeys + round * 4 * Nb);
  }

  SubBytes(state);
  ShiftRows(state);
  AddRoundKey(state, roundKeys + Nr * 4 * Nb);

  for (i = 0; i < 4; i++) {
    for (j = 0; j < Nb; j++) {
      out[i + 4 * j] = state[i][j];
    }
  }
}

void AES::DecryptBlock(const unsigned char in[], unsigned char out[],
                       unsigned char *roundKeys) {
  unsigned char state[4][Nb];
  unsigned int i, j, round;

  for (i = 0; i < 4; i++) {
    for (j = 0; j < Nb; j++) {
      state[i][j] = in[i + 4 * j];
    }
  }

  AddRoundKey(state, roundKeys + Nr * 4 * Nb);

  for (round = Nr - 1; round >= 1; round--) {
    InvSubBytes(state);
    InvShiftRows(state);
    AddRoundKey(state, roundKeys + round * 4 * Nb);
    InvMixColumns(state);
  }

  InvSubBytes(state);
  InvShiftRows(state);
  AddRoundKey(state, roundKeys);

  for (i = 0; i < 4; i++) {
    for (j = 0; j < Nb; j++) {
      out[i + 4 * j] = state[i][j];
    }
  }
}

void AES::SubBytes(unsigned char state[4][Nb]) {
  unsigned int i, j;
  unsigned char t;
  for (i = 0; i < 4; i++) {
    for (j = 0; j < Nb; j++) {
      t = state[i][j];
      state[i][j] = sbox[t / 16][t % 16];
    }
  }
}

void AES::ShiftRow(unsigned char state[4][Nb], unsigned int i,
                   unsigned int n)  // shift row i on n positions
{
  unsigned char tmp[Nb];
  for (unsigned int j = 0; j < Nb; j++) {
    tmp[j] = state[i][(j + n) % Nb];
  }
  memcpy(state[i], tmp, Nb * sizeof(unsigned char));
}

void AES::ShiftRows(unsigned char state[4][Nb]) {
  ShiftRow(state, 1, 1);
  ShiftRow(state, 2, 2);
  ShiftRow(state, 3, 3);
}

unsigned char AES::xtime(unsigned char b)  // multiply on x
{
  return (b << 1) ^ (((b >> 7) & 1) * 0x1b);
}

void AES::MixColumns(unsigned char state[4][Nb]) {
  unsigned char temp_state[4][Nb];

  for (size_t i = 0; i < 4; ++i) {
    memset(temp_state[i], 0, 4);
  }

  for (size_t i = 0; i < 4; ++i) {
    for (size_t k = 0; k < 4; ++k) {
      for (size_t j = 0; j < 4; ++j) {
        if (CMDS[i][k] == 1)
          temp_state[i][j] ^= state[k][j];
        else
          temp_state[i][j] ^= GF_MUL_TABLE[CMDS[i][k]][state[k][j]];
      }
    }
  }

  for (size_t i = 0; i < 4; ++i) {
    memcpy(state[i], temp_state[i], 4);
  }
}

void AES::AddRoundKey(unsigned char state[4][Nb], unsigned char *key) {
  unsigned int i, j;
  for (i = 0; i < 4; i++) {
    for (j = 0; j < Nb; j++) {
      state[i][j] = state[i][j] ^ key[i + 4 * j];
    }
  }
}

void AES::SubWord(unsigned char *a) {
  int i;
  for (i = 0; i < 4; i++) {
    a[i] = sbox[a[i] / 16][a[i] % 16];
  }
}

void AES::RotWord(unsigned char *a) {
  unsigned char c = a[0];
  a[0] = a[1];
  a[1] = a[2];
  a[2] = a[3];
  a[3] = c;
}

void AES::XorWords(unsigned char *a, unsigned char *b, unsigned char *c) {
  int i;
  for (i = 0; i < 4; i++) {
    c[i] = a[i] ^ b[i];
  }
}

void AES::Rcon(unsigned char *a, unsigned int n) {
  unsigned int i;
  unsigned char c = 1;
  for (i = 0; i < n - 1; i++) {
    c = xtime(c);
  }

  a[0] = c;
  a[1] = a[2] = a[3] = 0;
}

void AES::KeyExpansion(const unsigned char key[], unsigned char w[]) {
  unsigned char temp[4];
  unsigned char rcon[4];

  unsigned int i = 0;
  while (i < 4 * Nk) {
    w[i] = key[i];
    i++;
  }

  i = 4 * Nk;
  while (i < 4 * Nb * (Nr + 1)) {
    temp[0] = w[i - 4 + 0];
    temp[1] = w[i - 4 + 1];
    temp[2] = w[i - 4 + 2];
    temp[3] = w[i - 4 + 3];

    if (i / 4 % Nk == 0) {
      RotWord(temp);
      SubWord(temp);
      Rcon(rcon, i / (Nk * 4));
      XorWords(temp, rcon, temp);
    } else if (Nk > 6 && i / 4 % Nk == 4) {
      SubWord(temp);
    }

    w[i + 0] = w[i - 4 * Nk] ^ temp[0];
    w[i + 1] = w[i + 1 - 4 * Nk] ^ temp[1];
    w[i + 2] = w[i + 2 - 4 * Nk] ^ temp[2];
    w[i + 3] = w[i + 3 - 4 * Nk] ^ temp[3];
    i += 4;
  }
}

void AES::InvSubBytes(unsigned char state[4][Nb]) {
  unsigned int i, j;
  unsigned char t;
  for (i = 0; i < 4; i++) {
    for (j = 0; j < Nb; j++) {
      t = state[i][j];
      state[i][j] = inv_sbox[t / 16][t % 16];
    }
  }
}

void AES::InvMixColumns(unsigned char state[4][Nb]) {
  unsigned char temp_state[4][Nb];

  for (size_t i = 0; i < 4; ++i) {
    memset(temp_state[i], 0, 4);
  }

  for (size_t i = 0; i < 4; ++i) {
    for (size_t k = 0; k < 4; ++k) {
      for (size_t j = 0; j < 4; ++j) {
        temp_state[i][j] ^= GF_MUL_TABLE[INV_CMDS[i][k]][state[k][j]];
      }
    }
  }

  for (size_t i = 0; i < 4; ++i) {
    memcpy(state[i], temp_state[i], 4);
  }
}

void AES::InvShiftRows(unsigned char state[4][Nb]) {
  ShiftRow(state, 1, Nb - 1);
  ShiftRow(state, 2, Nb - 2);
  ShiftRow(state, 3, Nb - 3);
}

void AES::XorBlocks(const unsigned char *a, const unsigned char *b,
                    unsigned char *c, unsigned int len) {
  for (unsigned int i = 0; i < len; i++) {
    c[i] = a[i] ^ b[i];
  }
}

void AES::printHexArray(unsigned char a[], unsigned int n) {
  for (unsigned int i = 0; i < n; i++) {
    printf("%02x ", a[i]);
  }
}

void AES::printHexVector(std::vector<unsigned char> a) {
  for (unsigned int i = 0; i < a.size(); i++) {
    printf("%02x ", a[i]);
  }
}

std::vector<unsigned char> AES::ArrayToVector(unsigned char *a,
                                              unsigned int len) {
  std::vector<unsigned char> v(a, a + len * sizeof(unsigned char));
  return v;
}

unsigned char *AES::VectorToArray(std::vector<unsigned char> &a) {
  return a.data();
}

std::vector<unsigned char> AES::EncryptECB(std::vector<unsigned char> in,
                                           std::vector<unsigned char> key) {
  unsigned char *out = EncryptECB(VectorToArray(in), (unsigned int)in.size(),
                                  VectorToArray(key));
  std::vector<unsigned char> v = ArrayToVector(out, in.size());
  delete[] out;
  return v;
}

std::vector<unsigned char> AES::DecryptECB(std::vector<unsigned char> in,
                                           std::vector<unsigned char> key) {
  unsigned char *out = DecryptECB(VectorToArray(in), (unsigned int)in.size(),
                                  VectorToArray(key));
  std::vector<unsigned char> v = ArrayToVector(out, (unsigned int)in.size());
  delete[] out;
  return v;
}

std::vector<unsigned char> AES::EncryptCBC(std::vector<unsigned char> in,
                                           std::vector<unsigned char> key,
                                           std::vector<unsigned char> iv) {
  unsigned char *out = EncryptCBC(VectorToArray(in), (unsigned int)in.size(),
                                  VectorToArray(key), VectorToArray(iv));
  std::vector<unsigned char> v = ArrayToVector(out, in.size());
  delete[] out;
  return v;
}

std::vector<unsigned char> AES::DecryptCBC(std::vector<unsigned char> in,
                                           std::vector<unsigned char> key,
                                           std::vector<unsigned char> iv) {
  unsigned char *out = DecryptCBC(VectorToArray(in), (unsigned int)in.size(),
                                  VectorToArray(key), VectorToArray(iv));
  std::vector<unsigned char> v = ArrayToVector(out, (unsigned int)in.size());
  delete[] out;
  return v;
}

std::vector<unsigned char> AES::EncryptCFB(std::vector<unsigned char> in,
                                           std::vector<unsigned char> key,
                                           std::vector<unsigned char> iv) {
  unsigned char *out = EncryptCFB(VectorToArray(in), (unsigned int)in.size(),
                                  VectorToArray(key), VectorToArray(iv));
  std::vector<unsigned char> v = ArrayToVector(out, in.size());
  delete[] out;
  return v;
}

std::vector<unsigned char> AES::DecryptCFB(std::vector<unsigned char> in,
                                           std::vector<unsigned char> key,
                                           std::vector<unsigned char> iv) {
  unsigned char *out = DecryptCFB(VectorToArray(in), (unsigned int)in.size(),
                                  VectorToArray(key), VectorToArray(iv));
  std::vector<unsigned char> v = ArrayToVector(out, (unsigned int)in.size());
  delete[] out;
  return v;
}
